1. Field of Invention
This invention pertains to method and apparatus for recording and reading information stored in helical stripes on magnetic tape, and particularly to method and apparatus obtaining timing signals when reading information stored in helical stripes on magnetic tape.
2. Prior Art and Other Considerations
Numerous prior art patents teach the recording and reading of information stored in helical stripes on magnetic tape. In a helical scan arrangement, travelling magnetic tape is partially wrapped around a rotating drum so that heads positioned on the drum are contiguous to the drum as the drum is rotated. A write head on the drum physically records data on the tape in a series of discrete stripes oriented at an angle with respect to the direction of tape travel. The data is formatted, prior to recording on the tape, to provide sufficient referencing information to enable later recovery during readout.
Among such prior art teachings are the following United States Patents, all commonly assigned herewith and incorporated herein by reference:
(1) U.S. Pat. No. 4,843,495 to Georgis et al., entitled CYCLICAL SERVO ZONE TRACKING METHOD AND APPARATUS FOR HELICAL SCAN RECORDING DEVICES;
(2) U.S. Pat. No. 4,835,638 to Hinz et al., entitled APPARATUS AND METHOD FOR FORMATTING AND RECORDING DIGITAL DATA ON MAGNETIC TAPE; and,
(3) U.S. Pat. No. 4,845,577 to Georgis et al., entitled APPARATUS AND METHOD FOR ENABLING RAPID SEARCHING OF HELICALLY RECORDED MAGNETIC TAPE.
In reading information recorded in helical stripes on magnetic tape, it is imperative that timing signals be accurately developed. Timing signals are important for numerous functions. For example, the accuracy of the timing signals is critical for keeping the read head properly positioned over the helical stripes. Proper positioning of the read head is facilitated by servo mechanisms which read servo data on the tape. For the servo mechanisms to operate effectively, however, the servo data must be read in context of accurate timing signals.
It is an object of the present invention to provide an helical scan system which provides accurate timing signals for a helical scan recorder.
An advantage of the present invention is the provision of method and apparatus of dynamically developing timing signals for a helical scan system.
Another advantage of the present invention is the provision of helical scan method and apparatus using a simplified tape format.